Commit 681cc5e8 authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm: fix request-based DM to not bounce through indirect dm_submit_bio 



It is unnecessary to force request-based DM to call into bio-based
dm_submit_bio (via indirect disk->fops->submit_bio) only to have it then
call blk_mq_submit_bio().

Fix this by establishing a request-based DM block_device_operations
(dm_rq_blk_dops, which doesn't have .submit_bio) and update
dm_setup_md_queue() to set md->disk->fops to it for
DM_TYPE_REQUEST_BASED.

Remove DM_TYPE_REQUEST_BASED conditional in dm_submit_bio and unexport
blk_mq_submit_bio.

Fixes: c62b37d9 ("block: move ->make_request_fn to struct block_device_operations")
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 9c37de29

block/blk-mq.c

+0 −1
Original line number Diff line number Diff line
@@ -2265,7 +2265,6 @@ queue_exit: 
	blk_queue_exit(q);

	return BLK_QC_T_NONE;

}

EXPORT_SYMBOL_GPL(blk_mq_submit_bio); /* only for request based dm */



void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,

		     unsigned int hctx_idx)

drivers/md/dm.c

+12 −13
Original line number Diff line number Diff line
@@ -1633,18 +1633,6 @@ static blk_qc_t dm_submit_bio(struct bio *bio) 
	int srcu_idx;

	struct dm_table *map;



	if (dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) {

		/*

		 * We are called with a live reference on q_usage_counter, but

		 * that one will be released as soon as we return.  Grab an

		 * extra one as blk_mq_submit_bio expects to be able to consume

		 * a reference (which lives until the request is freed in case a

		 * request is allocated).

		 */

		percpu_ref_get(&bio->bi_disk->queue->q_usage_counter);

		return blk_mq_submit_bio(bio);

	}



	map = dm_get_live_table(md, &srcu_idx);

	if (unlikely(!map)) {

		DMERR_LIMIT("%s: mapping table unavailable, erroring io",
@@ -1727,6 +1715,7 @@ static int next_free_minor(int *minor) 
}



static const struct block_device_operations dm_blk_dops;

static const struct block_device_operations dm_rq_blk_dops;

static const struct dax_operations dm_dax_ops;



static void dm_wq_work(struct work_struct *work);
@@ -2113,9 +2102,10 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t) 


	switch (type) {

	case DM_TYPE_REQUEST_BASED:

		md->disk->fops = &dm_rq_blk_dops;

		r = dm_mq_init_request_queue(md, t);

		if (r) {

			DMERR("Cannot initialize queue for request-based dm-mq mapped device");

			DMERR("Cannot initialize queue for request-based dm mapped device");

			return r;

		}

		break;
@@ -3095,6 +3085,15 @@ static const struct block_device_operations dm_blk_dops = { 
	.owner = THIS_MODULE

};



static const struct block_device_operations dm_rq_blk_dops = {

	.open = dm_blk_open,

	.release = dm_blk_close,

	.ioctl = dm_blk_ioctl,

	.getgeo = dm_blk_getgeo,

	.pr_ops = &dm_pr_ops,

	.owner = THIS_MODULE

};



static const struct dax_operations dm_dax_ops = {

	.direct_access = dm_dax_direct_access,

	.dax_supported = dm_dax_supported,

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